Plug is an NGK B7EV, nice tan color, no sign of blistering, or tiny shiny spheres
So far the Comet has returned home on the back of my truck anytime I attempted a ride that was longer than 10 miles. I now realize the first time it stopped it must have seized, although it was free when I stopped, and started up again after it cooled off. The second time there was no doubt about what happened, that was mile 126 of my ownership. I am now at mile 205, new piston (7.3:1 diecast VOC part) and cylinder, and nervous about riding any distance.
I timed it with a degree wheel and the head removed, the tricky bit is making sure it does not move when tightening the atd. Next time I will make a piston stop out of an old spark plug. All my other bikes have points except my 07 Guzzi, many years ago I had an Atlas with a magneto. They were all much easier to set. Interesting factoid, I have a Chrysler 9.9 hp two cylinder water cooled outboard motor, the speed control twist grip moves the timing plate, a lot, not the carburetor. My first outboard, so I don't know if this is normal or unusual. It will empty the gas tank without blowing up as will all my other bikes.